Signs & symptoms — Panama TR4 Protect

Signs and symptoms of Panama TR4

External symptoms

What to look for:

yellowing of leaf margins and at the base of older leaves
entire leaves turning yellow and the leaf margins turning brown
dead leaves collapsing along the leaf stalk or at the junction of the stalk and pseudostem, forming a skirt of dead leaves around the stem of the plant
younger leaves remaining green and upright giving the plant a spiky appearance
stem splitting occasionally occurs at the base of the plant. The split is typically two or three layers thick, however, in the advanced stages of the disease, splitting can extend much higher up and deeper into the stem.

As the disease progresses, symptoms will become more obvious.

Tip:

Symptoms are more obvious at particular times of the year and crop stage. Environmental stress such as wet, dry or extremely hot conditions enhance the development of the disease. Crop stage is also a factor. As bunch development requires additional nutrients and water, this may promote expression of symptoms. For example, plants may look healthy until bunches emerge, then suddenly start to show leaf yellowing and wilt.

If you suspect a plant has Panama TR4, report it immediately to Biosecurity Queensland on 13 25 23 or click here to report it online.

Scroll through the below images to see examples of external symptoms:

Panama TR4 infected plant at an early stage. Note the signs of wilting of leaf base and yellowing of leaf margins.

Yellowing and browning of leaf margins
progressing to cover whole leaves.

Whole leaves becoming yellow to dark red
and brown and dying off. Leaf yellowing
and leaf edge death (browning).

Whole leaves turning yellow and starting
to die off. Affected leaves collapse and fall
around the pseudostem.

Skirt of dead leaves around the
lower part of the plant.

More extensive stem splitting may occur
at the base of the pseudostem with
advancement of the disease.

Symptoms in young plants

Tissue culture plants are disease free when they leave the laboratory but can be contaminated if they come into contact with contaminated soil or water. Bits and suckers carry a much higher risk of carrying and spreading the disease, even if they appear to be free from symptoms. Unexplained death of young plants in nurseries or after planting should be reported to Biosecurity Queensland. Planting material should always be sourced as tissue culture plants from an accredited QBAN nursery to minimise risk of spread of disease.

*Warning: Banana planting material should always be sourced as tissue culture plants from an accredited QBAN nursery to minimise risk of disease spread.*

Internal symptoms

Do not cut plants to look for internal symptoms of Panama TR4. Cutting or removing a symptomatic plant can spread infected material and stimulate the fungus to increase spore production which:

greatly increases the risk of disease spread within and off your property
reduces the chances of getting a suitable sample from the infected plant for diagnostic testing
puts the broader banana industry at risk.

If a symptomatic plant has been cut, it is important to notify Biosecurity Queensland immediately so that samples may be taken for diagnostic testing to confirm or exclude the presence of Panama TR4.

Internally, plants infected with Panama TR4 show discolouration of the vascular tissue in the corm and stem ranging from yellow to red through to dark brown or black. Symptoms are the same for young potted plants.

Scroll through the below images to see examples of internal symptoms:

Cross section of Panama TR4 infected plant. Note the discoloured vascular strands.

Cross section of a Panama TR4 infected plant and corm of a Panama TR4 infected plant.

Symptoms in young potted plants. Cavendish plant grown in a pot and infected with Panama TR4. Ducasse plant infected with Panama disease tropical race 1.

Other conditions and diseases that Panama TR4 can be confused with

In its early stages, the disease can be mistaken for:

nutritional disorders

drought

waterlogging

yellow sigatoka or leaf spot

Erwina

banana weevil borer damage

*Warning: If you’re not sure whether a plant has symptoms of Panama TR4 or another disease, you should still report it to Biosecurity Queensland on 13 25 23.*

Scroll through the below images to see examples of other conditions which can be confused with Panama TR4:

Generally, waterlogged plants will occur in large patches across plantations. Plants are deprived of oxygen and wilt.

Advanced symptoms of yellow sigatoka leaf spot. Note entire leaf may start to brown in early stages of yellow sigatoka.

Erwinia or bacterial corm rot affected plants can have external symptoms similar to plants infected with Panama disease. With Erwinia, in most cases, younger leaves
start to yellow first, whereas in Panama disease the older leaves are first to yellow — Erwinia or bacterial corm rot affected plants can have external symptoms similar to plants infected with Panama disease. With Erwinia, in most cases, younger leaves start to yellow first, whereas in Panama disease the older leaves are first to yellow. Plants affected by corm rot may also show discolouration of the vascular tissue in the pseudostem and corm similar to Panama disease. Erwinia has also been found in plants infected with Panama TR4.

Banana weevil borer is a potential vector for Panama disease.

What to do if you find a suspect plant

A suspect plant or plants should be immediately reported to Biosecurity Queensland on 13 25 23.

If you find a suspect plant you should:

Mark the plant with flagging tape or spray paint.
Record the location details of the plant (block, row, etc), to help find it again. Or take a GPS location point.
If you can, take pictures to help with identification.
Limit access to the suspect plant and alert other workers to avoid the vicinity of the plant.
Tell your supervisor or property owner who must immediately call Biosecurity Queensland on 13 25 23.